# US 2008/0187659 A1 · Methods for preparing thermal barrier coatings with high fracture toughness inner layer for improved impact resistance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0187659 A1 - Document ID: US20080187659A1 - Status: Published application - Kind: A1 - Application number: 11/774,878 - Filed: 2007-07-09 - Published: 2008-08-07 - Earliest claimed: 2004-07-26 - Inventors: Irene Spitsberg; Brett Allen Boutwell; Robert William Bruce - Web page: https://patentgrep.com/patent/US20080187659A1 ## CPC - C23C 14/08: Oxides (C23C14/10 takes precedence) - C23C 28/321: {with at least one metal alloy layer} - C23C 28/3215: {at least one MCrAlX layer} - C23C 28/325: {with layers graded in composition or in physical properties} - C23C 28/345: {with at least one oxide layer} - C23C 28/3455: {with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer} - C23C 28/42: {characterized by the composition of the alternating layers} - Y10T 428/12611: Oxide-containing component - Y10T 428/265: 1 mil or less - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Method for preparing reduced thermal conductivity thermal barrier coating having improved impact resistance for an underlying substrate for high temperature applications. An exemplary method includes depositing a first zirconia-containing ceramic composition having a c/a ratio of about 1.011 to about 1.016 and stabilized in the tetragonal phase by yttria, calcia, ceria, scandia, magnesia, india, lanthana, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof, and including about 0.3 to about 0.5% by weight lanthana, neodymia, gadolinia, and mixtures thereof The first material forms a high fracture toughness inner layer having a fraction of porosity of about 0.20 or less, and a thickness in the range of from about 0.5 to about 2 mils. The method includes depositing a ceramic material forming an outer thermal insulating layer overlying the inner layer and having a greater fraction of porosity than the inner layer. ## Claims ### Claim 1 A method comprising: a) optionally providing a bond coat layer on at least a surface of a metallic substrate; b) depositing on the bond coat layer, or on the surface of the substrate in the absence of the bond coat, a first material comprising a zirconia-containing ceramic composition having a c/a ratio of the zirconia lattice in the range of from about 1.011 to about 1.016 and stabilized in the tetragonal phase by a stabilizing amount of a stabilizing metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, lanthana, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof, and comprising from about 0.3 to about 0.5% by weight of a metal oxide selected from the group consisting of lanthana, neodymia, gadolinia, and mixtures thereof, wherein the first material is able to form a high fracture toughness inner layer, wherein depositing the first material includes controlling deposition conditions so that the inner layer formed thereby comprises a fraction of porosity of about 0.20 or less, and a thickness in the range of from about 0.5 to about 2 mils; and c) depositing on the inner layer a second material comprising a ceramic thermal barrier coating material able to form an outer thermal insulating layer, wherein depositing the second material includes controlling the deposition conditions so that the outer layer formed thereby has a greater fraction of porosity than the fraction of porosity of the inner layer; wherein the inner fracture toughness layer and the outer thermal insulating layer provide a thermal barrier coating for the substrate. ### Claim 2 (depends on 1) The method according to claim 1 wherein in (c), the second material is deposited so as to provide the outer layer with a thickness comprising about 50 to about 95% of a thickness of the thermal barrier coating. ### Claim 3 (depends on 1) The method according to claim 1 wherein in (b), depositing the first material includes utilizing a physical vapor deposition process. ### Claim 4 (depends on 1) The method according to claim 1 wherein in (c), depositing the second material includes utilizing a physical vapor deposition process. ### Claim 5 (depends on 1) The method according to claim 1 wherein in (c), the second material comprises at least one member of the group consisting of hydrated or unhydrated aluminum oxide, chemically phase-stabilized zirconia, and pyrochlores having a general formula A2B2O7 where A is a metal having a valence of 3+ or 2+, and B is a metal having a valence of 4+ or 5+, where the sum of A and B is 7. ### Claim 6 (depends on 1) The method according to claim 1 wherein in (a), the bond coat layer comprises at least one member of the group consisting of an overlay bond coating including MCrAlY alloys, an overlay bond coating including NiAl(Zr), a diffusion coating including noble metal diffusion aluminides, and a diffusion coating including simple aluminides. ### Claim 7 A method comprising: providing a thermal barrier coating on an underlying metal substrate by: a) forming an inner high fracture toughness layer overlaying the metal substrate, the inner layer having a fraction of porosity of about 0.20 or less, and a thickness in the range of from about 0.5 to about 2 mils, and sufficient to impart impact resistance to the thermal barrier coating, the inner high fracture toughness layer comprising a zirconia-containing ceramic composition having a c/a ratio of the zirconia lattice in the range of from about 1.011 to about 1.016 and stabilized in the tetragonal phase by a stabilizing amount of a stabilizing metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, lanthana, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof, and wherein the inner high fracture toughness layer comprises from about 0.3 to about 0.5% by weight of a metal oxide selected from the group consisting of lanthana, neodymia, gadolinia, and mixtures thereof, and b) forming an outer thermal insulating layer overlying the inner layer and comprising a ceramic thermal barrier coating material. ### Claim 8 (depends on 7) The method according to claim 7 further comprising: providing a bond coat layer adjacent to and overlying the metal substrate prior to providing the thermal barrier coating. ### Claim 9 (depends on 7) The method according to claim 7 wherein in (a), forming the inner high fracture toughness layer includes utilizing a physical vapor deposition technique, and wherein in (b), forming the outer thermal insulating layer includes utilizing a physical vapor deposition technique to provide a strain-tolerant columnar structure of the thermal barrier coating. ### Claim 10 (depends on 7) The method according to claim 7 wherein the thermal barrier coating has a thickness of from about 1 to about 100 mils. ### Claim 11 (depends on 7) The method according to claim 7 further comprising: c) providing an intermediate section of the thermal barrier coating between the outer thermal insulating layer and the inner fracture toughness layer, wherein the intermediate section includes at least one other thermal insulating layer adjacent to and overlying the inner fracture toughness layer and at least one other fracture toughness layer adjacent to and overlying the at least one other thermal insulating layer. ### Claim 12 (depends on 11) The method according to claim 11 wherein in (c) providing the intermediate section of the thermal barrier coating includes utilizing a physical vapor deposition technique. ### Claim 13 A method for preparing a thermal barrier coating for an underlying metal substrate, the method comprising the steps of: a) forming an inner high fracture toughness layer overlaying the metal substrate, the inner layer having a fraction of porosity of about 0.20 or less, and a thickness in the range of up to about 5 mils, and sufficient to impart impact resistance to the thermal barrier coating, and comprising a zirconia-containing ceramic composition having a c/a ratio of the zirconia lattice in the range of from about 1.011 to about 1.016 and stabilized in the tetragonal phase by a stabilizing amount of a stabilizing metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, lanthana, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof, and wherein the inner layer comprises from about 2 to about 7% by weight hafnia, and wherein the inner layer comprises from about 0.3 to about 0.5% by weight of a metal oxide selected from the group consisting of lanthana, neodymia, gadolinia, and mixtures thereof, and b) forming on the inner layer an outer thermal insulating layer adjacent to and overlying the inner layer and comprising a ceramic thermal barrier coating material. ### Claim 14 (depends on 13) The method according to claim 13 further comprising: c) providing an intermediate section of the thermal barrier coating between the outer thermal insulating layer and the inner fracture toughness layer, wherein the intermediate section includes at least one other thermal insulating layer adjacent to and overlying the inner fracture toughness layer and at least one other fracture toughness layer adjacent to and overlying the at least one other thermal insulating layer. ### Claim 15 A method for preparing a thermal barrier coating for an underlying metal substrate, the method comprising the steps of: a) forming an inner high fracture toughness layer overlaying the metal substrate, the inner layer having a fraction of porosity of about 0.20 or less, and a thickness in the range of up to about 5 mils, and sufficient to impart impact resistance to the thermal barrier coating, and comprising a zirconia-containing ceramic composition having a c/a ratio of the zirconia lattice in the range of from about 1.011 to about 1.016 and stabilized in the tetragonal phase by about 4 to about 7% by weight of a stabilizing metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, lanthana, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof, and wherein the inner layer includes at least one of hafnia or a metal oxide selected from lanthana, neodymia, gadolinia, and mixtures thereof, wherein if present, the hafnia is present in from about 2 to about 7% by weight, and wherein if present, the metal oxide is present in from about 0.3 to about 0.5% by weight; and b) forming on the inner layer an outer thermal insulating layer adjacent to and overlying the inner layer and comprising a ceramic thermal barrier coating material. ### Claim 16 (depends on 15) The method according to claim 15 further comprising: c) providing an intermediate section of the thermal barrier coating between the outer thermal insulating layer and the inner fracture toughness layer, wherein the intermediate section includes at least one other thermal insulating layer adjacent to and overlying the inner fracture toughness layer and at least one other fracture toughness layer adjacent to and overlying the at least one other thermal insulating layer.